How much more serious can it get?

I am sure every political blogger in the country is going to be posting something about Ruth Turner's arrest shortly, but I thought this Sky News article is interesting, it contains the quote:

Sky News' Crime Correspondent Martin Brunt said the latest development means the police investigation has gone in a "serious and bigger direction."

It almost implies it wasn't that serious before, despite the fact that the Prime Minister has been interviewed (albeit not under caution). The next serious step is surely either an interview under caution for Mr Blair or a file being passed to the Crown Proscution Service. If the former, that must surely mean a resignation?